Code Injection via Veriexec Bypass in Juniper Junos OS Kernel
CVE-2025-21590 is an improper isolation or compartmentalization vulnerability in the Juniper Networks Junos OS kernel. According to the provided content, a local attacker with high privileges and shell access can inject arbitrary code into the memory of legitimate processes, bypassing Junos OS Veriexec protections intended to prevent unauthorized binary execution. The issue is explicitly stated to be exploitable from the shell, not from the Junos CLI. Mandiant reporting in the supplied context further associates the flaw with process-memory code injection used to circumvent Veriexec and compromise affected Juniper MX routers. Affected releases include all versions before 21.2R3-S9; 21.4 before 21.4R3-S10; 22.2 before 22.2R3-S6; 22.4 before 22.4R3-S6; 23.2 before 23.2R2-S3; 23.4 before 23.4R2-S4; and 24.2 before 24.2R1-S2 and 24.2R2.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
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Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
12 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
An improper isolation flaw affecting Juniper MX routers that was exploited by UNC3886 in a notable 2025 zero-day campaign.
An arbitrary code execution vulnerability in Juniper MX Series routers.
A previously noted Juniper Junos OS vulnerability referenced only as part of vendor security history; no technical details are provided in the content.
A Junos OS vulnerability exploited to bypass Veriexec protections and enable malicious code injection into legitimate processes.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.